Telephone-exchange system



Aug. 10,1926. 1,595,072 f H. C. CAVERLY TELEPHONE EXCHANGE SYSTEM Filed March 9, 1923 3 sheds-sheet 1 Incoming Sdecior /m/en/a/f' Har/y '6. aller/y.

Aug. 10 1926. ,595,072

. H. c. cAvERLY TELEPHONE XCHANGE SYSTEM 1923 3 Sheets-Sheet 2 Filed March 9 //7 Ue/vfar. f/ar/g/ C. ayer/y H. C. CAVERLY TELEPHONE EXCHANGE SYSTEM lAugn 9 Filed March 9 1923 3 Sheets-Sheet 5 Patented Aug. l0, 1926.

arras sereni orties.

HARRY C. CAVERLY, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application iled 'March 9, 1923. SeraI No. 623,902.

This invention relates to telephone exchange systems employing mechanical switching devices Vand more'particularly to impulse recording and translating devices for such systems. v

The number or" omces which may be connected by a given exchange system is indicated by the number of digits in the orilce code. Obviously, a one-digit code would permit selection among not more than 10 otiices; a two-digit code among not more than 100 ofiices; a three-digit code among ,not more than 1000 voiiices and so on. In practice these numbers would be decreased by the reservation of the digit 0 for calls to operator and the absorption ot a single impulseto avoid false operation due to accident. A V'further decrease would be caused by the di'liculty of finding` oiice names having certain initial combinations of letters. It is thus probable that a one-digit code would serve for 8 ofr'ices; a two-digit code for perhaps oii'ices; a three-digitcode for possibly 300 oihces.

in exchange areas employing a two-digit or a three-digit code, connections are usually established through the intermediation of a sender which records the impulses sent out by the subscriber and then automatically controls the routing of the call and the connection to the called subscribers line in accordance with this setting of the registers. lrot only does the number of the registers increase with the number of digits employed but the complexity ci the circuits and apparatus necessary for translating the setting oi" the code registers increases enormously. v

In exchange areas, therefore, where the ultimate number of oiiices does not greatly exceed the capacity oi' a two-digit system it is highly desirable to iind means for increasing that capacity, without being forced to extend the system to a full three-digit basis.

it is the object ot this invention to provide a. sender which will respond either to a two-digit or a three-digit office code, and at the same time retain the simplicity of the two-digit sender.

1n accordance with a feature. of the invention, means are provided for recording a plurality ot digits on one of the registers and then translating the combined settings ot the several registers.

An additional feature is the `use of a registering device arranged to record a variable number of diO'its, and circuits for accomplishing the discrimination whereby the number ot digits to be recorded is determined.

A further lfeature of the invention is the use of a plurality of translating devices and the method of discriminating between the translators. K

Since complete telephone exchange systems of the type to which the sender of the present invention lis applicable, have been disclosed in a number of patents and applications, the automatic vswitches and select.- ing circuits have been indicated only diagrammatically in the drawing illustrating this application. Reference is made to application for patent oi' Ottmar H. Kopp, Serial No. 105,294 f led April 28, 1921, issued as Patent No. 1,509,434, Sept. 23, 1924, for a more complete disclosure of such circuits. rThe invention is, of course, capable ot use in other systems than that shown in the drawing.

Referring to the drawing, Fig. l shows a calling subscribers substation. Switches by means of which a connection maybe eX- tended to a called substation are diagrammatically indicated, as is a sender selector. The lower portion of the ligure shows some ot the relays ot the sender. Fig. 2 shows the code registers and Fig. 3 shows the translator switches which control district and otiice selections.

rThe general operation of the system s bstantially similar to that described in the above mentioned Patent ilo. 1,509,434', issu-ed to O. H. Kopp Sept. 23, 1024. `'Vhen the calling subscriber at substation 100 removes his receiver from the switchhook, a line switch 101 is put into operation to select a trunk leading to an idle district selector suoli as 102. The seizure of such trunk puts into operation a sender selector 103 which associates an idle sender with the selected trunk circuit.

Each sender is provided with a plurality of step by, step registering devices. These registering devices may be oi' any desired character but are preferably of the type shown and described in Patent 1,472,465, granted October 30, 1923, to O. F. Forsberg and R. M. De Vignier. A register controlling switch is utilized to direct the successive series of pulses to the registering devices.

lilith the regular code the controlling switch directs a single series of pulses to each of the registering devices. `ifilhen a special code is to be used a preliminary series of pulses of predetermined number is sent out which places the first register' in a position in which a circuit is closed for preventing the advance of the register controlling switch at that time. r)The second series of pulses is then recorded on a dierent section of the lirst register. -he controlling switch is permitted to advance at the close of this series of pulses to direct the succeeding series to the succeeding register or registers. Any digit may be used as a preliminary digit for the special code, but obviously, it cannot at the same time be used as the rst digit of any of the regular codes. lt is also obvious that the capacity of any of the registers may be increased in the same way, or that the arrangement may be applied to a system employing any number of registers. Also, more than one digit may be used for the preliminary digit, where flexibility is more desirable than a maximum increase in capacity.

The translator switch is of suoli simple construction that it has not been necessary to provide a drawing of its mechanism. Two arcuate contact banks each com arising a number of contact sets, and each contact set comprising a plurality of contacts, are arranged side by side and supported by a suitable frame. A brush shaft carrying two brush sets arranged to cooperate with the contact sets is mounted in operative relation to the contact banks in the same frame. The brush sets are 130O apart in rotation, that is, they are diametrically opposite one another on the shaft, and the arrangement is such that when one brush completes its travel over its associated contact bank, the other brush set will begin its travel over its associated contact bank. The power is transmitted to the shaft from a constantly rotating shaft by,` means of clutch discs controlled in the manner commonly employed in the construction of sequence switches. rlhe power source is indicated in the present disclosure by the magnet 307, 327, 347 or 367. Since the brushes are driven at high speed, a stop magnet represented in the drawing by magnet 303, 328, 343 or 368 has been provided for each translator switch in order to insure the brushes stopping on the desired terminal set. As the number of functions to be controlled by the translator switch exceeds the number of arcs usually provided on a switch of this type", two switches 300 and 320 are provided and are rotated and stopped simultaneously so that they form in combination essentially one translator. ln order to increase the possible number of oilice registrations, a second pair of translator switches 340 and 360 is provided which are also controlled simultaneously, together with means for discriminating between the pairs of translator switches as will be described later.

The detailed operation of the system is as follows:

When an idle sender is selected and the brush set of the sender selector comes to rest on the terminals leading to thesender, a circuit is completed from ground, lefthand winding of the balancing coil 104, contact and brush 1.05 of sender selector 103, contact and brush of line switch 101, through the subscribers substation, brush and contact of line switch 101, brush 106 and contact of sender selector 103, winding relay 107 to grounded battery. Relay 10'? operates and closes a circuit from ground at its armature and front contact, winding of relay 103 to grounded battery. Relay 10S operates and closes a circuit from ground at its front contact and armature, winding of relay 106 to grounded battery. Relay 106 closes the dialing tone circuit by way of source of dial tone 109, right-hand winding of balancing coil 104, conductor 110, normal contact 201 and brush 202 of register 200, conductor 203, normal Contact 261 and brush 262 of register controlling switch 260, conductors `275 and 263 to ground at the outer right armature and front contact of relay 106. A tone is induced in the circuit of the right hand winding of the balancing coil notifying the subscriber that he may dial. Relay 106 also prepares the pulse circuit eX- tending 'from the back contact of relay 107, left-hand armature and front'contact of relay 106, conductor 111, winding of relay 264, brush 265 and contact 266 of register controlling switch 260, winding of stepping magnet 203, back contact and armature of relay 204, resistance. 205 to grounded battery.

When the subscriber dials the lirst digit of the office code the circuit of relay 107 is opened a number of times corresponding to the digit dialed. At each interruption of the circuit, relay 107 deenergizes and its armature falls back opening the circuit of relay 108 which, however, is slow to release and remains energized during these short interruptions of its circuit. The -deenergization of relay 107 closes ground from its armature to the pulse circuit above traced, causing relay 264 and .stepping magnet 203 to operate in series. Magnet 203 releases at the close o-f each pulse to advance register 200. Relay 264 being slow to release remains energized until the completion Vof the series of pulses, when it also deenergizes. The operation of relay 264, 'clses a circuit :trom grounded battery, resistance 267 ,-winding of magnet268, armature and front contact ot relay 264, conductor 269 lto ground at the inner right armature and front contact of relay 106. Magnet 268 is energized and remains energized, until the deenergization or relay 264 at the close of the series of pulses, releases it to advance lthe register controlling switch 260 to its next set of contacts. It will be noted that each deenergiz'ation of relay 107 also closes venergizes and at itsV right-hand armature closes ground to relay 108 to insure kthat relay 108 remains energized during the 1nterruptions of its circuit and at its lefthand armature also maintains the circuit of magnet 203 until this magnet completely attracts its armature, thus insuring the operation ot magnet 203 and the advance ot the register. n

With switch 260 in `position 2, the pulsing circuit extends from brush 265 and contact 272 ot switch 260 through the winding of magnet 231, backcontact and armature of relay204, resistance 205 to grounded battery. Each interruptionot the pulsing circuit due to the dialing of the second digit advances register 230 one step. As in the case ot register 200, relay 264 remains energized throughout the series of pulses and holds the circuit or magnet 268 closed. At the completion of the series of pulses, magnet 268 releases and advances the register control switch 2,60 to its third position, in which position the pulse circuit is closed through to the thousands. register (not shown). The setting ot the numerical registers takes place in a manner similar to that of the code registers and is as shown and described inthe above identified Patent No. 1,509,434. The circuit above ltraced for relay 112 is completed in the second position of switch'260 through brushes 271 and 265 and their .second contacts and the armature and back contact or magnet231-to linsure the.

proper advance of register 230 in response to eachimpulse.

The actual setting of the registers and translators for a representative two-digit code will now be described.

Assume that the called substation is located in an orifice called Astor. The code dialed in this case is A-S, which will vresult in the sending out of two series of pulses.

comprising two pulses and seven pulses respectively. For the arrangement of letters and numbers on a typical dial, reference may be made to Fig. 33, Bureau -ot Standards circular No. 112, Telephone Service. ln this case register 200 comes'to rest with its brushes resting `on their second ofi-normal contacts :and the brushes oi register 230 come to rest on their seventh oil-normal contacts. As soon as switch 260 advances to position 3 after register 230 is set, a circuit is closed `from ground at the outer right armature and `232 and its seventh oft-normal contact 233.

conductor 234, to contacts on 'arcs 306 and 326, 316 and 336, 346 and366, 356 and 376 Yof the translator switch'es 300, 320, 340, and

360 thus marking thesecontacts with ground. The circuit for magnet 307 may be traced Vfrom grounded battery, winding o't' magnet 307, armature and baclr contact of stop magnet 308, inner right-hand armature and bachr contact of relay 380, conductor 381 outer right-hand armature and 'front contact or relay 206 to ground. rl`he circuit for magnet 327 may be traced from grounded battery, winding of magnet 327, armature and back contact'ot stop magnet 328, outer right-hand armature and back Contact of relay 380, conductor 382, inner right-hand armature and front contact of relay 206 to ground.r The operation of magnets 307 and 327 moves the brushes or switches 300 and 320 ever their contacts. vWhen contacts 317 and 337, which 'ot 316, outer lett armature and back contact ot relay 383, inner lelt armature and back contact of relay 330 inner armature and back contact of relay 384, winding ot stop magnet 308, resistance 309 to grounded battery. A similar circuit is completed from ground on the contact 337, brush of arc 336. inner lertarmature and back contact ofrelay 38.3,'outer lett armature and bac'l: contact or' relay 380, outer lett armature and back contact or relay 384` winding' of stop magnet 328,*resistance 329 to groundedbattery. Although contacts 310 and 330'are also marked with a ground the circuits l*through the brushes or' arcs 306 and are open at the lett armatures of Lrelay 383 4and A'no circuit can loe closed through these contacts. The stop magnets 308 and 328 operate, opening the circuit of rotary magnets 307 and 327 thus bringing the translator switch to rest on the selected row of contacts.

Had the desired office been ESsex register 230 would have stopped in the same position but register 200 would have been brought to rest on its third olf-normal contact. Tlvlith 'the registers in these positions ground is f ain placed on conductor 234:. However, with register 200 on its third contact and the register control switch in position 2 or beyond, a circuit is closed from grounded battery, winding of relay 383, conductor 385, Contact 212 and brush Q13 of register 200, contact 270 and subsequent contacts and brush 209. of register control switch 260, conductors 275 and 2.68 to ground at the outer right armature and front Contact of relay 106. Relay 383 operates in this circuit. lViththe register set as above the same set of contacts is marked with ground on translator arcs 305, 316 etc. The circuits of stop magnets 308 and 328, however, lead by Way of the back contacts and armatures of relay 384e and left back contacts and armatures of relay 380, and the left alternate contacts of relay 383 to the brushes of arcs and respectively. Therefore the stop magnets operate when the rotary contacts 30T and 327 have brought the brushes et translators 300 and 320 to contacts 310 and 330 instead of contacts 31'? and 337.

The operation of setting the translating devices When a three-digit o'tlice code is dialed will now be described.

Assume that the preliminary digit used for the special three-digit code is 9. This may be incorporated in the number as listed in the directory either as a preliminary numbei', for example, 9 TER-ie or a letter designation may be used, thus WESton or to avoid confusion for the subscriber Who may have become accustomed to dialing only two code digits, the number may be Written lVlston T followed by the usual four digit number.

assume then that it is desired to reach a subscriber in the o'liice Whose code as indicated above corresponds to the digits 9 3 7. The dialing of the digit 9 will cause registcr 200 to be set upon its ninth O'lnOrmal contact in Which posit-ion a circuit is closed from grounded battery, resistance 26'?, Winding of magnet 268, conductor 276, Contact 211i and brush 215 of register 200, conductors 275 and 263 to ground at the outer right armature and front contact of relay 106. This circuit prevents the release of magnet 268 at the completion of the first set of pulses, holds switch 260 in its fist or normal position, and permits the second series of impulses to advance the brushes of register 200 onto the second half of its bank. It

may thus be seen hoW the dialing of a predetermined digit will permit the registration of a plurality of digits on a given register.

Tf the second digit dialed is three, the brushes of register' 200 Will advance to their twelfth terminal at which time they will come to rest, and since the above traced holding circuit of the. register control svvitch 260 has been opened this switch will advance to its second position. The third series of impulses corresponding to the digit 7 will place register 230 on its seventh terlninal. A circuit for again placing ground potential on conductor 234e and the corresponding contacts of the translator test banks is prepared. l/Vith register 200 pon sitioned on the second half of its bank a circuit is closed as soon as relay Qtll'releases at the close of the second series of impulses. This circuit extends from ground at the inner right armature and front contact of relay 10G, conductor 269, right normal contact of relay 26a, conductors 277 andl 216, brush 217 and its twelfth contact (or any contact from ll to 18), conductor 218, Winding of relay 386, Winding of relay 380 to battery and ground. Relays 386 and 380 operate in this circuit. Relay 386 closes a circuit extending from ground at its outer right armature and front contact, Winding of relays 387 and 388 in series, to battery and ground. The same ground extends to relay 384 by a branch circuit. These three relays also operate. The operation of relays 386, 387 and 388 opens the selection controlling paths to the arcs of translat r switches 300 and 320 and closes the paths to the arcs of translator svitches 340 and 360. Theoperation of relay 380 transfers the energizing circuits to be closed by relay 206 from magnets 307 and 327 to magnets 347 and 367, while the joint operation of relays 380 and 384e transfers the stop circuits from stop magnets 308 and 328 to magnets 348 and 368. rThe setting Vof the register 200 on its twelfth contact alsocoinpletes the previously traced circuit for relay 383 which operates. Thus it may be seen that the positioning of register 200 on a set of contacts in the second half of its bank by two series of impulses brings translator 34(0 300 int-o use instead of translator 30C-320.

Relay 206 is operated as before as soon as register control switch 260 advances to position 3 to close ground from conductor 263 through the registers to terminals 350 and 370 and also to close the circuits for the rotary magnets 347 and 367 of the translator 31l0 360. The circuit of magnet 347 may be traced from ground, outer right armature and front Contact of relay 206, conductor 381, inner alternate Contact lof relay 380, armature and back contact of stop magnet 348, Winding of magnet 347 to battery and ground. The circuity for magnet367 may be` traced from ground,.inn er right armature and front contact4 of relay 206,

. conductor 382g outer alternate contact of .re-

lay 380, armature and back contact of stop magnet 43637 Winding of magnet 367 to battery and ground. lhen the brushes oarcs 346 and 366 reach the grounded terminals 350 and 370 a circuit is completed from l() 1 nets 347 and 367 and bringing the brushes to rest on the ,desired set ofv terminals.

As soonas the brushes of either translator corne to rest on grounded terminals,circuits are completed Yfrom the grounded terminals on .the'hunting arcs, right contacts of relay 383, lett contactsof relay 380; conductors 380 and 390 to the Winding of relays 278 and 279. lfheserelays operate and lock up to ground by Way of conductor 381 and the outer 'right armature and front Vcontact ot relay 206. Relay 279provides a snbstitute holding ground for relay 206 at lts inner left armature and rontcontact, vand the joint operation of thevtWo relays closes circuits for advancing the sender and sender control sequence switches (not shown) to theirneXt positions in which circuits are closed by vvhich the translator controlsy the selection of the desired oliice. The operation of these sequence vswitches is the* same as thatof the corresponding switches in the disclosure loi the above Vmentioned Patent No. 1,509,434.

The method ofabsorbing a single impulse such as might arise from an accidental move ment or' the s'witchhook is of interest. l/Vith theregister control switch 260 in its normal position and. register 200 in position y,1 (which Wouldresult from a single 1nterruption of the circuit), a circuit may be traced from ground at the, outer right varmature and Jfront contact of relay 106,` conductors 263 and,27,5, brush215 and'its first ott-normal contact 2.19, .conducton 27 6,. Winding oli' register control,magnet` 263, resistance 267 to; grounded; battery,t hc1ding ,the umagnet operated, au'crprventng its' fareste to 'advancevthe snitch to gitsgneft, positlon. .At

the; same.' tim-@Ya circuit i,ssclcsed; `from A grounded battery, l right .Wi jing. of' .relay 204 inst- @Qntaet ,2,20 and bres. .317 Of lglsf terv200, conductors 216 and 277, normally closed contact of relay 264, conductor 269 to ground at the inner right armature and front contact or" relay 106.. Relay 204 opcrates and at its right armature opens thecircuit of magnet 203. When relay 107 again falls backl in response to an interruption of the line circuit, a circuitvis completed from ground,'armature 'andbaclr contact of relay 107, lett armature and front contact of relay 106, conductor 111, Winding of relay 264, brush 265 and contact 266 ot register control switch 260,` inner lefthand armature andfront contact and left Winding of relay 204,` resistance 221 to battery and ground. Relay 264 operates and at its left armature clos'esfthe circuit for magnet 268 and opens the yoriginal energizing circuit of relay 204. Relay 2.04 remains energized in the above traced circuit through its left winding untilv the end yof the pulse when it' releases. '.Relay 264 being slow to release does not close its back contact untilv after lthe relay 204 hasY releasedl and closed the `battery lead to magnet 203.v IfY this pulse is followed by a series of pulses, the nent pulse causes the energization of magnet 203, and. advances register 200 to its second position and lthe rest of the action proceeds as before. Should the second pulse also be a false or single pulse so vthat relay 264 deenergizes directly after it, magnet 203 is not energized and brushes 215 and 217 remain on their first oit-.normal contact so that the holding circuit for magnet 26S is maintained yand the circuitfor relay 204 is closed again as soon as relay 264 deenergizes and remains closed until suchltime as a series of impulses is received or the snbf scriber hangs up. y c

With, translator 300320 or 340-360 positioned upon the set of contacts marked by ground on arcs 306 and326 or 316vand 336, etc., circuits are completed through the various arcs for performing the necessary functions involved in selecting the desired oliice. One arc controls the setting of a switch in accordance With the class of call. Other arcs have their contacts connected to counting relays for controlling the selection of the proper brush Iand group on the district selector, and the proper brush and group yon thefotlice selector.v At the same time other arcs connect resistances into the 'fundamental circuit to' equalize the.' resistanceintroduced yas soon as;,Selectionl progrosses" beyond thev district selector., Other .arcs'have theiry terminals connected tok advanc`e`the'-s`ender squencesvvit'ch through the positions fololiic'e' select'ioinffwhere; the destination sought il ac directly bly disnea; For are functions a'r feartfd treat@ y 4@aaar- ...41; as" are fune:

. and the sender and sender control sequence Cil switches have. advanced in response to the energization of relays 278 and 279, cam 225 of the sender control sequence switch is closed. A circuit is established from ground, cam 225, brushv 226 and an o-normal contact, armature, back contact, and winding ot magnet 203, armature and back contact of relay 204, resistance 205 to grounded battery, thus forming a self-interrupting circuit for magnet 208 to restore switch 200 to normal. When this switch reaches its normal position the ground on cam 225 is extended by way ot brush 22S and its normal contact to brush and its ott-normal contacts, armature, back contact and winding of magnet 231, armature and back contact of relay 204, resistance 205 to grounded battery. Magnet 231 operates in this self-interrupting circuit and steps register 230 back to normal.

As soonas selection is completed the circuit ot relay 10'? is opened by the district selector and this relay deenergizes. rllhe deenero'ization oit relay 107 releases relay 108 which closes ground to conductor 111i, brush 283 of register control switch 250 and its oilnormal contacts, conductor 284, armature, back contact and winding ot magnet 268, resistance 267 and grounded battery, forming a self-interrupting circuit tor magnet 268 which steps the register control switch back to its normal position. Upon the return of the register control switch to normal the sender control switch is advanced and cam 210 is opened, releasing relays 278, 279 and 206, after which the sender and sender control sequence switches are restored to normal and the sender is in condition to serve a subsequent call.

The translator switches have no normal position, but remain in any given position until advanced by the operation ot the rotary magnets in accordance with subsequent setting ot the registers.

What is claimed is:

l. In a switching system, a plurality ot switches, switch controlling devices operated in response to series of impulses, andmeans for discriminating. between said switches in accordance with the number of said series of impulses.

2. A, s et ot registering devices, means to position said registering devices in response to av variable number of series of impulses,

and a translating device positioned under the joint control or said registering device-s.

8. In a telephone system, means tor generating current impulses, a series of auto-4 matic switches positioned by series or current impulses, a control device normally operated to direct a single series ot impulses to each ot said switches in turn, and means whereby said control device may be operated to direct a plurality of series ot impulses to a given switch. v

4. 1n a telephone system, a series of autoinatic switches positioned by series ot current impulses, a control device normally operated to direct a single series of impulses to each ot' said switches in turn, and means for holding sain control 'device in one position while a plurality ot series of impulses are directed to one switch.

5. 1n a telephone system, a plurality of automatic switches, a multi-position control device, means for normally operating said control device to Idirect a single series c impulses to a dierent switch in each positan thereof and means for holding said control device in itslirst position while two series of impulses are directed Vto the first ot said switches.

6. 1n a telephone system, a plurality of automatic switches, a multi-position control device, means 'for normally operating said control device to direct a single series of current impulses to a 'diierent switch in each position thereof, and means responsive to a preliminary series of impulses of predetermined number to hold said control device in its first position while a second series oft impulses is directed to the first of said switches.

7. ln a registering system, a pair of registering devices each normally positioned by a series ot current impulses, and means whereby the first of saidV registering devices may be positioned by two series ot current impulses and the second of said registering devices may be positioned by a third series of current impulses.

8. 1n aregistering system, a registering device normally positioned by a single series ot current impulses 1n one group of positions and means whereby a predetermined' preliminary series of impulses will cause said device to be positioned in a second group of positions by a second series ot impulses. y

9. In a selection controlling system a plurality of selector switches, a plurality ot registers, means for positioning each otsa-id registers by a single series of impulses to control the setting of said switches in one` group of choices and means for positioning said registers by a number of series ot impulses greater than the number of registers to control the setting of said switches in other groups ot choices. l

10. In a selection controlling system, a plurality of selector switches, a plurality of registers, means for positioning each of said registers by a single series or' impulses to .control the setting ot' said switches in one group of choices, means to posit-ion said reg isters by a number of series of impulses greater than the number of registers to control the setting of said switches in other groups of choices and means to determine the group of choices within which said switches are to be set in accordance with the number of series of impulses employed in setting the registers.

rl1. In a selection controlling system, a plurality ot selector switches, a plurality of registers each normally positioned by a single series of current impulses, a transn lator normally operated to prepare circuits determined bythe joint positioning of said registers to control the setting of said switches within one group ot choices, means to position said registers by a number or series of impulses greater than the number of said registers and to operate said translator to control the setting of said switches within a second groupot choices.

12. In a selection controlling system, a plurality of registers each normally positioned by a series of current impulses, means whereby one of said registering devices may be positioned by a plurality of current impulses, a translating device and means `tor variably operating said translating device in accordance with the number of series ot impulses used to position said registers.

13. In a selection controlling system, a

primary register having two sections, and a secondary register each normally positioned by a single series of current impulses, a translator normally operated to prepare circuits determined by the joint position of the primary and secondary registers to control selection within one group of choices, and means operative by a preliminary se.- ries of impulses of predetermined number, to position said primary register in its second sec-tion and to operate said translator to control selection within a second group of' choices.

14. In a selection controlling system, a primary register having two sections, and a secondary register each normally positioned by a single ,series ot current impulses, a register controlling device for directing the series of impulses to the primary and secondregisters in turn, and advancing at the close ot each series ot impulses, a translator normally operated to prepare circuits determined by the joint positioning' of the pri- -niary and secondary registers to control se lection within one group of choices, and means operated by a preliminary series of impulses of predetermined number to hold said register controlling device in its first position during a second series of impulses to position said primary register in its second section and to operate said translator to control selections within a seco-nd group of choices.

In witness whereof, I hereunto subscribe my name this 7th day of March A. D. 1923.

HARRY C. CAVERLY. 

